Alien DAC v1.1 Construction Thread
Mar 11, 2007 at 3:17 AM Post #632 of 1,562

GarlicKnots

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Ok. Unfortunately more problems on my last build.

I am getting 3.3 and 4.72.

When I connect it to my computer it says something akin to "USB device not recognized...one of the usb devices has malfunctioned..etc."

What should I look for?

Any other readings I should take?
 
Mar 11, 2007 at 5:53 AM Post #633 of 1,562

splaz

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The USB pins on the schematic. With mine, pin ahhh... 2 or 3 I think was open. Cleaned that joint up and it was recognised.

Then next problem was my right output was fried...
rolleyes.gif


I'd check pins 2 through to 9 thoroughly, also probably 1 and 28 as I don't think it would operate correctly without a clock.
 
Mar 15, 2007 at 3:40 PM Post #636 of 1,562

amb

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Quote:

Originally Posted by Sinbios /img/forum/go_quote.gif
Quick question, what happens if Vin is below Vout for the regulator? Does it work in pass through mode, shut down completely, or actually add noise?


It would drop out of regulation and work as a "pass through", down to a certain threshold voltage, then it would probably just shut down below that.
 
Mar 20, 2007 at 11:14 PM Post #637 of 1,562

scratch.music

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I'm building the Alien DAC as part of a headphone amp that I am building for a project and can't find any place that has the adjustable voltage regulators in stock. I just recently picked up a PCB off a forum member that had an extra, looks like all the distributors are sold out. Either REG101UA or REG102UA I checked: Digikey, Mouser, Arrow, Newark and Avnet, which are all the distributors listed for Michigan (I'm an MSU student) on TI's website. My complete project needs to be done in a month, does anyone have any spare regulators, knows of a place I can order them online or any alternatives that would work?
Also, if you have other spare parts required to build the DAC I could take them off your hands. The only part I have so far is the PCM2702 and plan on ordering the rest along with parts for my headphone amp this week. I can pay with paypal.
Thanks,
 
Mar 20, 2007 at 11:17 PM Post #638 of 1,562

MisterX

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Quote:

does anyone have any spare regulators, knows of a place I can order them online or any alternatives that would work?


Sure.
Pm me your address info and I will drop one in the mail in the morning.
smily_headphones1.gif
 
Mar 24, 2007 at 2:10 AM Post #640 of 1,562

error401

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Quote:

Originally Posted by AngryGuy /img/forum/go_quote.gif
So, I want to make one of these but it appears I'm a bit late to the party. Is anyone still selling all the parts needed for it, or a kit or something?


HeadFier jrossel has apparently gotten permission from amb to provide kits and raw PCBs for this project. We should see these kits and boards appear fairly soon, from what he's said. Maybe send him a PM and see how his progress is going?

He has a website at http://glassjaraudio.com/ with his other kits. They're apparently well regarded.
 
Mar 24, 2007 at 2:23 AM Post #641 of 1,562

amb

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Quote:

Originally Posted by error401 /img/forum/go_quote.gif
HeadFier jrossel has apparently gotten permission from amb to provide kits and raw PCBs for this project.


Not me, but it was alf. Apparently jrossel is getting pcbs manufactured so hopefully they will be available again soon.
 
Mar 25, 2007 at 3:22 PM Post #643 of 1,562

GarlicKnots

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Well guys, my alien dac debacle continues. I need some help troubleshooting. I added some pictures.

Here is where I am now:

1) I get 3.3
2) I get 4.72 (where I have the adjustable reg at)
3) Installed ASIO driver, etc.

When I connect the DAC to a computer I get the error:
Quote:

USB device not recognized

One of the USB devices attached to this computer has malfunctioned and Windows does not recognize it...


I've tried this on my computer and my brother's computer with the same error.

I have two meters, I have tested continuity with both of them and there doesn't seem to be continuity. I will admit I'm a bit unsure on how to test continuity since it seems too easy. I've checked with a 15x microscope also.

Here are some pictures. I socketed c2 to make it easier to work on IC1.

I believe (hope) that I'm missing something very simple. Suggestions?

I don't take pictures well, and my camera's zoom isn't too good so I couldn't get closer pictures.

DSCN0134-1.jpg


DSCN0123.jpg


DSCN0132.jpg


DSCN0138.jpg
 
Mar 25, 2007 at 3:50 PM Post #644 of 1,562

AndrewFischer

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You may have some solder bridges on the dac chip.

Looks like pins 27 and 28 may be bridged. Maybe 25 and 24. hard to tell from the photo. You could try some flux and solderwick and try and pick up some of the extra solder.

I'd also check all the pins are connected. I had to reflow solder on both of mine. If all else fails, remove the 2702 and try again. I used 3 chips to make two working DACs.
redface.gif
 
Mar 25, 2007 at 4:43 PM Post #645 of 1,562

GarlicKnots

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Quote:

You may have some solder bridges on the dac chip.

Looks like pins 27 and 28 may be bridged. Maybe 25 and 24. hard to tell from the photo. You could try some flux and solderwick and try and pick up some of the extra solder.

I'd also check all the pins are connected. I had to reflow solder on both of mine. If all else fails, remove the 2702 and try again. I used 3 chips to make two working DACs.


Both 27/28 are bridged. They both go to ground. I also bridged 13/14 since they go to ground. That is OK, I believe?

If 25/24 were bridged would I still get the correct 4.7 reading @ the 5V pad?

You are correct, some pins may not be connected. I'm going to reflow 10/11 and 1 and 15.

Q. If I'm getting 3.3 and 4.7, should I refrain from touching 2-9 and 16-26?
 

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